All of the current solar cell panel arrangements using conventional solar cells in continuous flat arrays depend on direct or normal exposure to solar radiant energy to produce their rated power outputs.
The present ground based solar electrical cells and panels utilizing silicon or other types of solar cells are intended for direct conversion of the sun's energy into D.C. electrical power, and currently their wide scale application is not economically practical because of excessive production costs, and generally poor cost/effectiveness ratios,
Most of the present ground based solar panel arrangements that have been proposed and utilized make use of large tracts of open, flat lands, where the solar cell panels are arrayed in an orderly direction and attitude to make optimum use of the solar radiant energy.
While this method is logical and practical for economical direct solar electrical conversion in remote and rural areas of the conntry, it does not provide for the high density panel concentration required for urban areas, where electrical power is always in large demand, and sometimes in short supply.
At the present time there are four basic types of solar cells available and in use for various solar panel arrays, with further development effort proceeding to improve power output and efficiencies. The latest gallium-arsenide type of cell is in the development stage and showing considerable promise for high efficiencies at moderate costs.
The most widely used solar cells at this time are the silicon-type which produce moderate electrical outputs, but at excessively high costs per unit cell. Work is continuing to be done on silicon cell variations, specifically in improving production techniques to sharply lower the end cost of these cells. The cadmium-sulphide solar cells used in some solar panel systems are less efficient than equivalent silicon cells, but are correspondingly less expensive, so that they are still actively used in experimental solar conversion systems.
The least effective, and least used of the solar cells, is the low cost selemium cell, which will probably be dropped from further use as the other types of solar cells are evolved and improved.
The cost of all the various types of solar cells must be drastically reduced and/or conversion efficiencies raised significantly before these solar cells can be incorporated into cost/effective solar conversion system for urban applications.
Some types of solar cells utilize small, multiple magnifier lenses which are molded into the transparent plastic housings to increase solar concentration and corresponding power output. While this construction boosts the power output slightly, the increase is generally insignificant.
The use of reflective sunlight concentrators is a way to increase power output and lower costs, but there are limitations to utilizing this method because of available surface space and heat buildup. Parabolic reflectors and plastic Fresnel lenses may be used to concentrate sunlight onto the centers of each solar cell, provided that adequate heat dissipation means are applied to the conversion arrangement.
Another problem which must be faced and resolved economically is the necessity for movable or sun-following solar panel arrays. The effectiveness of fixed solar panel arrays is seriously limited to receiving optimum solar energy during only a portion of one-days sunlight, while the moving, sun-following solar panels can receive the ideal normal solar radiation over approximately ten hours or 150 degrees of angular travel, under ideal exposure conditions.
The sun following solar panels may be actuated by a pendulum weight drive arrangement, with manual resetting at the end of each day, or by a fully automatic drive may be selected which uses a small percentage of the D.C. electrical power generated by the solar panel array.
This present high density, -third dimension geometry solar panel concept is advocated as a means of utilizing the lower cost, -less efficient solar cells, such as CdS cells, and some types of silicon cells into dense panel arrays which require substantially less solar exposure surface area per unit cell area, by setting the cells in-depth, at oblique angles to normal solar radiation exposure.
In a previously advocated high density solar panel arrangement, multiple closely spaced solar cells were mounted on both faces of a flat, elongate solar panel. A pair of side reflectors directed the sun's rays onto the underside, unexposed solar cells. This refelection method onto flat solar panels is not as effective as the presently advocated tri-panel reflective design, where the underside solar cells are doubled in number, in two rows, and the reflectors set parallel to each row of solar cells for normal solar exposure between the solar cells and the reflectors.
Modifications of the basic tri-form solar panel are possible such as a diamond or squarish cross-section, with four rows of solar cells, but these shapes will result in about the same output-effectiveness as the basic tri-form shaped panels.
The multiple solar tri-panels and other types of high density panels are intended for mounting on flat, nearly level roofs of various urban buildings for optimum exposure to solar radiation.